Antenna modules of this kind are used in automotive engineering to enable radio services such as broadcast reception, GPS information, vehicle access control system, control of the immobilizer system, engine start release, setting of personal preferences, passenger compartment monitoring, parking aid, tire pressure monitoring, etc.
Services of these kinds are sometimes separated into services for the exterior of the motor vehicle and services for the interior of the motor vehicle, said services also being transmitted on different frequencies (LF, HF) or bands. In contrast, some services require a transmission that is effective beyond the limits of the motor vehicle, such as, for example, the communication between ID transmitter (key) and the control device for the access control system, passenger compartment monitoring and engine start or, as the case may be, control of the immobilizer, in order to identify the precise position of a person and initiate corresponding actions as a function of said position.
In order to enable these different services partly on different frequencies for the exterior of the motor vehicle and for the interior of the motor vehicle, a plurality of antennas are typically arranged inside the motor vehicle and outside on the exterior of the motor vehicle.
However, arranging a plurality of antennas possibly including power supply (control devices and/or active antennas) and forwarding of the transmitted signals requires an increased cabling overhead and consequently, given the increased number of services available in today's motor vehicles, is disadvantageously time-consuming and cost-intensive in production as well as in maintenance and any subsequent installation and repair. Added to this is the problem of realizing a precise electromagnetic separation of the antennas or, as the case may be, their transmitting and/or receiving fields in view of the increased number of antennas.